This invention relates to the formation of novel glass compositions, and particularly to the formation of glass compositions wherein the principal components comprise silver halides.
Glass is an ideal optical material because it can be easily formed into different shapes such as lenses, prisms and fibers. Silicate glasses in practical dimensions have an absorption edge at about three to four .mu.m in the infrared spectral range and other oxides also absorb in the middle infrared, so glasses of other compositions, such as halides, have been sought for use in the middle infrared.
The middle infrared has several advantages for a variety of optical applications: longer waveguide cores can be fabricated, high power laser energy can be transmitted, and heat detection and measurement can be made. Various crystalline materials have been suggested for infrared optical fibers, B. Bendow and S. S. Mitra, "Fiber Optics: Recent Advances in Research and Development", Plenum, N.Y., 1979, pp. 105-118; 119-122; T. J. Bridges, J. S. Hasiak, and A. R. Strand, Opt. Lett. 5, 85-86 (1980); D. A. Pinnow, A. L. Gentile, A. G. Standlee, A. J. Timper, and L. M. Hobrock, Appl. Phys. Lett. 33, 28-29 (1981), but these fibers are difficult to fabricate and are fragile. Some glasses such as ZnCl.sub.2 are being developed for use in the 2-5 .mu.m region, L. G. Van Uitert and S. H. Wemple, Appl. Phys. Lett. 33, 57 (1978), and a new class of fluoride glasses, A. Lecoq and M. Poulain, J. Noncryst. Solids 34, 101 (1979), M. G. Drexhage, C. T. Moynihan, and M. Saleh, Mat. Res. Bull. 15, 213-219 (1980), based on ZrF.sub.4 and HfF.sub.4 are useful up to about 8 .mu.m.
In an article entitled "Glass Forming Substances", K. J. Sun proposed the formation of pure silver halide glasses and glasses comprising mixed silver halides. Proposed examples include pure silver chloride or a mixture of silver chloride and silver fluoride. Attempts to form silver halide glasses according to Sun's proposals have been unsuccessful due to crystal formation.
Silver halides generally have good infrared radiation absorption properties. Compared with conventional glass forming materials, silver halides demonstrate relatively low absorption properties for radiation in the infrared portion of the spectrum, particularly in the area of 10 to 12 microns. It is desirable to form glasses using silver halides to facilitate the fabrication of components for use in infrared systems, such as infrared laser system, and also for the purpose of forming glass fibers, which may be used for transmission of infrared laser radiation.
It is therefore an object of the present invention to provide a glass material, the principal components of which are silver halides.